1. Field of the Invention
This invention is directed toward a method for making the composite structural member employing a flange member.
The invention is further directed toward an apparatus for use in making the composite structural member.
2. Description of the Related Art
Composite structural members, such as I-beams, are known. These composite structural members usually have separate flanges joined to a central web in making beams, particularly I-beams. The materials usually employed, in both the flanges and webs, are wood; wood-based, engineered products such as plywood; and metal such as steel. Composite structural members employing metal flanges with a wooden web are efficient and cost-effective. The wooden web provides a desirable insulation factor, compared to a metal web and allows openings to be easily made through it for services. The metal flanges provide high strength and stability for the member. In addition the metal flanges can be provided with integral fasteners formed by punching teeth out of the flanges. The teeth can be easily pressed into the web to securely join the flanges to the web.
One form of a composite structural member employing a wood-based web and metal flanges is shown in U.S. Pat. No. 4,281,497. Each metal flange member is formed with side walls extending from a base. Fasteners are usually formed integrally in the side walls of the flange. An edge of the web is located against the base and the side walls of the flange, with the fasteners formed therein, are bent about the base against the web to form a pocket to receive an edge portion of the web. At the same time the fasteners in the side walls are pressed into the web to fasten the flange to the web. In this construction, the fasteners are formed in the flange, in a separate operation, before the flange and web are assembled. This additional step makes the assembling of the composite member relatively expensive.
It is preferred to have the side walls of the flange member doubled so as to have the pocket formed by side walls and base of the flange, which pocket receives an edge portion of the web, more rigid and thus more likely to tightly confine the web making the bearing capacity of the web stronger and thus making the composite member stronger. An example of such a construction is shown in U.S. Pat. No. 4,937,998. However, using metal flange members, with doubled side walls, with a wooden web, and with integral fasteners in the doubled side walls, is expensive. Openings must be provided in the inner wall panel of the doubled side wall to allow passage of the integral fasteners formed in the outer panel of the doubled side wall. The integral fasteners, and the openings for the fasteners, are formed in the flange in a separate operation, before assembly of the flange and web, again making the assembly relatively expensive.
Both types of composite members described above have the fasteners, joining the flange to the web, integrally formed in the flange in a single layer of sheet metal. The sheet metal layer must therefore be relatively thick to provide fasteners strong enough to penetrate the web. Using relatively thick sheet metal flanges, which may be thicker than the thickness required to provide the necessary strength for the composite member, increases the cost of the members.